The present invention relates to an improvement in a tool holding device or chuck that includes a plurality of radially compressible tool gripping segments separated by axial slits in a body member of the chuck device.
The industry is continuously seeking improvements in tool holding chuck devices that will substantially increase the gripping strength or slip torque of such devices without substantially increasing the manufacturing cost or complexity of the devices.
The industry is also turning towards a type of chuck device referred to as a "quick-change" chuck wherein a tool bit can be readily inserted and removed from the chuck by manipulation of a sleeve member or other actuating device without the necessity of wrenches or other tools. With particular types of these chucks, the tool shank is inserted into a bore defined by segments in the chuck body. The segments are separated by axial slits. A compressive force is applied to the segments to compress or flex the segments radially inward to grip upon the tool shank. Examples of this type of chuck device are contained in U.S. patent application Ser. No. 08/808,890 filed on Feb. 28, 1997, by the assignee of this application. Embodiments of the chucks described and disclosed in the pending '890 application will also be discussed in this application.
The importance of increasing gripping strength or slip torque is of particular concern in high speed machine applications, such as routers, dry wall cutters, laminate trimmers, etc. An improved chuck device for use in these applications is disclosed and claimed in the pending '809 application cited above. The present invention has particular relevance to these chucks in that it substantially increases the gripping strength and slip torque of the chucks without adding to the manufacturing process or cost.